1. Field of the Invention
The present invention relates to a pressure relief device for the cooling system of an internal combustion engine under pressure. During the maintenance of internal combustion engines, it is common practice to desire access to the liquid in the cooling system while the cooling system is under pressure and while the liquid in the cooling system is hot. Such is the case in some processes for the change-over of used antifreeze/coolant in a cooling system to a new antifreeze/coolant when the charge-over process is to be carried out while the used antifreeze/coolant is at a sufficiently high temperature, e.g., 180.degree. F. and higher, and the thermostat of the engine remains in an open position.
2. Description of the Prior Art
Review of the prior art has not revealed any apparatus directed to the relief of pressure in a cooling system of an internal combustion engine by means of a hose associated with the cooling system. It is well known in the prior art to provide pressure relief to a cooling system by use of a two-step radiator cap. Such a radiator cap is provided with an intermediate position between the closed position of the radiator cap and removal of the radiator cap whereat the cooling system is vented to ambient pressure so as to reduce the pressure of the cooling system. In practice a cloth or bag is placed over the radiator cap to prevent uncontrolled spraying of antifreeze/coolant as the cooling system is vented. Unfortunately, the undirected discharge of antifreeze/coolant at the radiator cap is undirected and provides a safety hazard as the hot antifreeze/coolant sprays from the radiator cap.
A review of the prior art was conducted in: Class 73, Subclasses 863, 863.11, 863.12, 863.81 and 863.85; Class 123, Subclass 41.55; Class 137, Subclasses 317 and 318; Class 141, Subclass 330; Class 184, Subclasses 1.5 and 105.1; and Class 222, Subclasses 81 and 82. The following patents were located by the search:
______________________________________ U.S. Pat. No. PATENTEE ______________________________________ 1,538,273 Darrow 1,806,363 Narbo 2,254,102 Cruse 3,762,432 Peterson 4,524,811 Taylor ______________________________________
U.S. Pat. No. 1,538,273 discloses a top for liquid containers of the type used for milk. The top comprises a conically shaped tube with a point to penetrate the wall of the container, a tab in tube for accessing the liquid in the container and a disk for contacting the container wall for maintaining the top in the correct position.
U.S. Pat. No. 1,806,363 discloses a dispensing device for a container comprising a hollow cylindrical member having one end pointed for perforating a wall to provide an outlet opening with a shoulder to limit insertion of the hollow cylindrical member into the container. A flexible conduit may be attached to one end of the hollow cylindrical member.
U.S. Pat. No. 2,254,102 discloses a device for connecting a hydrometer to the circulating cooling system of an internal combustion engine having a tube with one end for a hydrometer with the other end bevelled or otherwise sharpened to penetrate a hose connection between the engine and the radiator. A combination of a downwardly tapered boss and a nut on a thread portion of the tube assembly acts to hold the hydrometer in place after the boss penetrates the hose and the nut is tightened against the outer hose surface.
U.S. Pat. No. 3,762,432 discloses a pressure test plug for use with high pressure system by insertion through a resilient valve core in a threaded valve connector.
U.S. Pat. No. 4,524,811 discloses an engine oil sampling device which employs a hollow needle to access oil in the engine through a centrally bored self-sealing access plug connected with a wall of the engine in communication with the oil.
The present invention is to be distinguished from the above discussed patents in that the patents do not deal with a pressure relief device for an automotive cooling system. Although U.S. Pat. No. 2,254,102 discloses a hydrometer for use with the cooling system of an internal combustion engine, the patent does not disclose any means for providing a pressure relief apparatus for a cooling system. The present invention provides such a pressure relief apparatus for pressure relief of a cooling system of an internal combustion engine which contains a hot liquid under pressure, i.e., at a pressure greater than ambient pressure.